A204860 - OEIS

%I #11 Jul 28 2020 11:20:13

%S 102,382,1437,5352,20113,75595,283877,1066520,4007148,15055157,

%T 56564804,212519195,798454799,2999883555,11270857666,42345767978,

%U 159097399097,597745236156,2245790151901,8437664012699,31701168874413,119104542808892

%N Number of (n+2) X 3 0..1 arrays with every 3 X 3 subblock having three equal elements in a row horizontally, vertically, diagonally or antidiagonally exactly two different ways, and new values 0..1 introduced in row major order

%C Column 1 of A204867.

%H R. H. Hardin, <a href="/A204860/b204860.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 2*a(n-1) +7*a(n-2) -8*a(n-4) +22*a(n-6) +41*a(n-7) +22*a(n-8) +13*a(n-9) -270*a(n-10) +64*a(n-11) +392*a(n-12) -424*a(n-13) +24*a(n-14) -228*a(n-15) +304*a(n-16) +200*a(n-17) -192*a(n-18) +32*a(n-19).

%e Some solutions for n=3

%e ..0..0..0....0..1..1....0..0..0....0..1..1....0..0..1....0..1..1....0..0..0

%e ..1..0..0....1..0..0....1..1..1....0..1..1....0..1..1....1..1..0....1..0..1

%e ..0..1..1....0..0..0....1..1..0....1..0..1....0..1..1....1..1..0....1..1..0

%e ..1..1..1....0..1..1....0..0..0....0..0..0....0..0..1....1..0..0....1..1..0

%e ..0..1..0....0..0..1....0..1..1....0..0..1....0..0..1....0..1..0....0..1..1

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 20 2012